Protecting catalytic activity of a SAPO molecular sieve

ABSTRACT

This invention is directed to a method of making an olefin product from an oxygenate feedstock and a method of protecting catalytic activity of a silicoaluminophosphate molecular sieve. The methods comprise providing a silicoaluminophosphate molecular sieve having catalytic sites within the molecular sieve; shielding the catalytic sites to protect from loss of catalytic activity; and contacting the protected sieve in its activated state with an oxygenate feedstock under conditions effective to produce an olefin product before undesirable loss of catalytic activity. Undesirable loss in catalytic activity occurs when activated molecular sieve contacting the oxygenate feedstock has a methanol uptake index of at least 0.15.

[0001] This application is a divisional of U.S. application Ser. No.09/391,770 filed Sep. 8, 1999 which claims priority to U.S. ProvisionalPatent Application No. 60/137,933, filed Jun. 7, 1999, the entiredisclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] This invention relates to a method of protecting the catalyticactivity of a SAPO molecular sieve, and to a method of making an olefinproduct by contacting the activated catalyst with an oxygenatefeedstock. In particular, this invention relates to a method ofprotecting the catalytic activity of a SAPO molecular sieve by shieldingthe catalytic sites of the molecular sieve.

BACKGROUND OF THE INVENTION

[0003] Silicoaluminophosphates (SAPOs) have been used as adsorbents andcatalysts. As catalysts, SAPOs have been used in processes such as fluidcatalytic cracking, hydrocracking, isomerization, oligomerization, theconversion of alcohols or ethers, and the alkylation of aromatics. Inparticular, the use of SAPOs in converting alcohols or ethers to olefinproducts, particularly ethylene and propylene, is becoming of greaterinterest for large scale, commercial production facilities.

[0004] As is known in the development of new large scale, commercialproduction facilities in the commodity chemical business, many problemsarise in the scale up from laboratory and pilot plant operations. Thisis particularly a concern in catalytic reaction systems where largescale operation will be several orders of magnitude larger than typicalpilot scale facilities. For example, conventional laboratory scaleprocesses of making olefin products from oxygenate feed are conductedwith catalyst loads of about 5 grams. Conventional large pilot plantoperations may utilize as much as 50 kg of catalyst, making on the orderof 20 kg/hr ethylene and propylene product, but this is neverthelessminuscule in comparison to what a large scale, commercial productionfacility would produce, if one were in existence today. It would bedesirable to operate large scale, commercial production facilities,which may require a catalyst loading of anywhere from 1,000 kg to700,000 kg, producing anywhere from 600 to 400,000 kg/hr of ethylene andpropylene product, if a reliable method of providing such a largequantity of catalyst could be used.

[0005] Operating large scale, commercial production facilities clearlypresents great challenges in the development of the catalystproduction-to-use chain. By production-to-use chain is meant the entirearea of activities beginning with the production of molecular sieve,including such activities as receipt of starting materials, on throughthe crystallization process. Also included in the production-to-usechain are intermediate activities which include formulation of the sievewith binders and other materials, activation of the manufactured sieveand finished catalyst; storage, transport, loading, unloading ofmolecular sieve and finished catalyst; as well as other practicesassociated with the handling and preparation of the sieve and finishedcatalyst for its ultimate use. The production-to-use chain ends at thepoint when the molecular sieve is introduced into the reaction system.For purposes of this invention, the end of the production-to-use chaindoes not necessarily mean the instant when the molecular sieve isintroduced into the reaction system, since large scale systems are verylarge and instantaneous measurements are not practically feasible. Inlarge scale systems, the production-to-use chain may be considered ascompleted some time within 12 hours of loading an activated catalystinto the reaction system.

[0006] Since information to date relating to production of olefinproducts by catalytic conversion of oxygenate feedstock has been limitedto laboratory and small pilot plant activities, little if any attentionhas been paid to the problems associated with the intermediateactivities in the production-to-use chain. For example, little attentionhas been focused on the impact of storage, transport, etc. on catalystactivity, since small scale activity is rather easily manageable. Whiletoday only relatively small quantities of catalyst are stored andtransported, large quantities of materials will need to be handled forcommercial operations. This may require storage of large quantities ofsieve and catalyst materials for considerable periods of time, atmultiple locations, and under rather rigorous industrial conditions.

[0007] As the management of sieve and catalyst in the catalystproduction-to-use chain expands in volume and complexity, there is thelikelihood that millions of dollars will be tied up in catalystinventory, and the value of the sieve and catalyst will be lost ifquality is not maintained at every step. Loss of quality willnecessarily translate to loss of product quality as well as loss ofproduct quantity, and these product losses could far outweigh the costof the sieve and catalyst.

[0008] Although there has been some work published relating to theintermediate activities in the catalyst production-to-use chain, few ofthe problems associated therewith have been addressed. For example, U.S.Pat. No. 4,681,864 to Edwards et al. discuss the use of SAPO-37molecular sieve as a commercial cracking catalyst. It is disclosed thatactivated SAPO-37 molecular sieve has poor stability, and that stabilitycan be improved by using a particular activation process. In thisprocess, organic template is removed from the core structure of thesieve just prior to contacting with feed to be cracked. The processcalls for subjecting the sieve to a temperature of 400-800° C. withinthe catalytic cracking unit.

[0009] U.S. Pat. No. 5,185,310 to Degnan et al. discloses another methodof activating silicoaluminophosphate molecular sieve compositions. Themethod calls for contacting a crystalline silicoaluminophosphate withgel alumina and water, and thereafter heating the mixture to at least425° C. The heating process is first carried out in the presence of anoxygen depleted gas, and then in the presence of an oxidizing gas. Theobject of the heating process is to enhance the acid activity of thecatalyst. The acid activity is enhanced as a result of the intimatecontact between the alumina and the sieve.

[0010] Briend et al., J. Phys. Chem. 1995, 99, 8270-8276, teach thatSAPO-34 loses its crystallinity when the template has been removed fromthe sieve and the de-templated, activated sieve has been exposed to air.Data are presented, however, which suggest that over at least the shortterm, this crystallinity loss is reversible. Even over a period ofperhaps two years, the data suggest that crystallinity loss isreversible when certain templates are used.

[0011] EP-A2-0 203 005 also discusses the use of SAPO-37 molecular sievein a zeolite catalyst composite as a commercial cracking catalyst.According to the document, if the organic template is retained in theSAPO-37 molecular sieve until a catalyst composite containing zeoliteand the SAPO-37 molecular sieve is activated during use, and ifthereafter the catalyst is maintained under conditions wherein exposureto moisture is minimized, the crystalline structure of the SAPO-37zeolite composite remains stable.

[0012] As seen from the disclosure herein, we have now found that anactivated SAPO molecular sieve will exhibit a loss of catalytic activitywhen exposed to a moisture-containing environment, and that this lossoccurs between the time the catalyst is activated and even after aslittle as one day of storage. More importantly, we have now found thatthe loss of catalytic activity is not reversible after a certain periodof time. It is desirable, therefore, to obtain an activated SAPOmolecular sieve and incorporate that molecular sieve into a catalyticprocess before loss of catalytic activity becomes too great.

SUMMARY OF THE INVENTION

[0013] In order to overcome at least one of the many problems inherentin the prior art, the invention provides a method of protectingcatalytic activity of a silicoaluminophosphate molecular sieve which isto be used in converting an oxygenate feedstock to an olefin product,particularly an olefin product comprising ethylene, propylene, or both.Protection against loss of catalytic activity is provided by coveringcatalytic sites of the molecular sieve with a shield prior to contactingwith the oxygenate feedstock. Catalytic contact, i.e., contact offeedstock with molecular sieve under catalytic conversion conditions,must be made before a parameter defined herein as the methanol uptakeindex drops too low. In addition, the weight percent methanol conversionof the catalyst, determined at standard parameters, should not beallowed to drop below a minimum percentage. Drops in methanol uptakeindex or methanol conversion which are too low will likely result in acatalyst that is of little or no practical use in a large scale process.

[0014] In this invention, the shield can be provided in several ways.The shield can be the template material which is actually used to makethe molecular sieve. As is known in the art, the template forms theporous structure within the molecular sieve. Conventionally, thetemplate is removed by calcining, essentially burning it from themolecular sieve. Leaving the template within the intracrystallinestructure for the proper time will, however, protect the catalytic sitesthat are within the porous structure of the molecular sieve.

[0015] Even if the template is removed the molecular sieve can still beprotected by providing other types of shields to cover the catalyticsites. For example, carbonaceous material can be used as a shield. Oneway of providing the carbonaceous material is to partially calcine orburn the template, leaving enough carbon material within the pores ofthe molecular sieve to provide the shield.

[0016] An anhydrous environment can also act as a shield, even when thetemplate or carbonaceous material has been removed. An anhydrousenvironment is one that is depleted in water content. It can be either agas or a liquid environment.

[0017] In a particular embodiment of protecting catalytic activity of asilicoaluminophosphate molecular sieve, the invention comprisesproviding a silicoaluminophosphate molecular sieve having catalyticsites protected against loss of catalytic activity by covering with ashield, and introducing the molecular sieve into an oxygenate reactionsystem, wherein the molecular sieve has a methanol uptake index of atleast 0.15 at time of contact with oxygenate under conditions effectiveto convert the oxygenate to olefin product. To provide protection forstorage and transporation the shield should be provided within themolecular sieve for at least 12 hours prior to contact with oxygenate.Longer storage and transporation conditions may require that the shieldbe provided within the shield for longer periods of time, e.g., 24hours, 1 month, or perhaps many months.

[0018] The protected molecular sieve is of great benefit in large scalecommercial processes of making olefin product from oxygenate feedstock,particularly making olefins containing ethylene or propylene fromfeedstock comprising methanol or dimethyl ether. In a particularembodiment of making an olefin product from an oxygenate feedstock, theinvention is to a method which comprises providing asilicoaluminophosphate molecular sieve having catalytic sites within themolecular sieve; providing a shield to protect the catalytic sites fromcontact with water molecules; removing the shield; and, after removingthe shield, contacting the sieve with an oxygenate feedstock underconditions effective to produce an olefin product, wherein the activatedsieve contacting the oxygenate feedstock has a methanol uptake index ofat least 0.15, preferably 0.4, more preferably at least 0.6, and mostpreferably at least 0.8.

[0019] In another embodiment, there is provided a method of making anolefin product from an oxygenate feedstock, comprising removing atemplate from a silicoaluminophosphate molecular sieve and contactingthe molecular sieve with the oxygenate feedstock under conditionseffective to convert the feedstock to an olefin product before themethanol uptake index drops below 0.15, preferably 0.4, more preferably0.6, most preferably 0.8.

[0020] It is desirable that the activated molecular sieve that iscontacted with oxygenate feedstock have a methanol conversion of atleast 10 wt. % at a standard time on stream (TOS) of 5 minutes and aweight hourly space velocity (WHSV) of 25 hr⁻¹. Preferably the molecularsieve should have a methanol conversion of at least 15 wt. % at astandard time on stream of 5 minutes and a WHSV of 25 hr⁻¹, morepreferably a methanol conversion of at least 20 wt. % at a standard timeon stream of 5 minutes and a WHSV of 25 hr⁻¹.

[0021] The shield can be removed ex situ (outside the reactor per se) orin situ. In a preferred embodiment, the shield is the template and thetemplate is removed outside of the reactor unit per se in order tominimize product contamination, particularly nitrogen contamination dueto nitrogen components within a nitrogen-containing template that may beused as the shield.

[0022] In another preferred embodiment, once the shield has beenremoved, the molecular sieve can be maintained at a temperature of atleast 150° C., with no shield, with little if any catalyst activity lossdue to exposure of catalytic sites with moisture. In this embodiment,the molecular sieve is preferably maintained at a temperature of 150 to800° C., more preferably at a temperature of 175-600° C., and mostpreferably at a temperature of 200-500° C. in order to maintain catalystactivity.

[0023] Preferably, the template is a nitrogen-containing hydrocarbon.Preferably, the nitrogen-containing hydrocarbon is selected from thegroup consisting of a tetraethyl ammonium hydroxide salt,cyclopentylamine, aminomethyl cyclohexane, piperidine, triethylamine,cyclohexylamine, tri-ethyl hydroxyethylamine, morpholine, dipropylamine,pyridine, isopropylamine and mixtures thereof The silicoaluminophosphatemolecular sieve is preferably selected from the group consisting ofSAPO-5, SAPO-8, SAPO-11, SAPO-16, SAPO-17, SAPO-18, SAPO-20, SAPO-31,SAPO-34, SAPO-35, SAPO-36, SAPO-37, SAPO-40, SAPO-41, SAPO-42, SAPO-44,SAPO-47, SAPO-56, metal containing forms thereof, and mixtures thereof.

[0024] The oxygenate feedstock is preferably selected from the groupconsisting of methanol; ethanol; n-propanol; isopropanol; C₄-C₂₀alcohols; methyl ethyl ether; dimethyl ether; diethyl ether;di-isopropyl ether; formaldehyde; dimethyl carbonate; dimethyl ketone;acetic acid; and mixtures thereof. More preferably, the oxygenatefeedstock is methanol or dimethyl ether.

[0025] The silicoaluminophosphate molecular sieve can provided with abinder material, and the template can be removed by heating at atemperature between 200° C. and 800° C. In order to convert theoxygenate to olefin product, the process is preferably performed at atemperature between 200° C. and 700° C.

[0026] The present invention will be better understood by reference tothe Detailed Description of the Invention when taken together with theattached drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027]FIG. 1 shows methanol conversion using a morpholine basedmolecular sieve, which has been aged under various environmentalconditions;

[0028]FIG. 2 shows methanol uptake of a morpholine based molecularsieve; and

[0029]FIG. 3 shows methanol conversion using a SAPO-34 molecular sievewhich has been stored under various conditions.

DETAILED DESCRIPTION OF THE INVENTION

[0030] SAPO catalysts, in particular, are susceptible to structuralchanges as a result of continued exposure to even low levels ofmoisture. Such authorities as Paulitz et al., Microporous Materials, 2,223-228 (1994), however, have shown through X-ray diffration (XRD),nuclear magnetic resonance (NMR), infrared (IR) and nitrogen (N₂)adsorption analyses that the structural change is largely reversible.Nevertheless, we have found that although adsorption analyses indicatethat structural change is largely reversible, this data cannot be reliedupon as an indicator of loss of catalytic activity. In particular, wehave found that SAPO molecular sieves lose catalytic activity when thecatalytic sites are exposed to an open air environment for as little asa few hours after activation, and that loss of catalytic activity isirreversible after a certain point.

[0031] The possibility of irreversible loss of catalytic activitypresents a problem in the commercial production-to-use chain wherestorage and transport of molecular sieve and catalyst can be over arelatively long period of time. For example, the as manufacturedmolecular sieve can be stored anywhere from 12 hours to many months,perhaps as long as one year, before its final use as an activatedcatalyst.

[0032] SAPO molecular sieve, as well as the SAPO molecular sieve blendedwith other catalyst material, can be protected from negative effects ofmoisture by properly shielding catalytic sites within the molecularsieve. Proper shielding can be accomplished in a variety of ways. Thecatalytic sites can be shielded by maintaining a template within themolecular sieve, by covering the sites with a carbonaceous material orby maintaining the sieve, even without a template, in an anhydrousenvironment. Removing template or carbonaceous material from the activesites of the molecular sieve results in an activated molecular sieve,meaning that the molecular sieve has its catalytic sites open and readyto contact feedstock. The anhydrous environment serves as a shield forthe activated molecular sieve in the sense that it shields activecatalyst sites from contact with open air conditions, particularlymoisture in the air.

[0033] In order to use the SAPO molecular sieve as a catalyst, theshield must be removed such that the catalytic sites of the molecularsieve can be open to contact feedstock. Once the shield is removed,however, the catalytic sites are open to contact with moisture or othercomponents that may be present in the localized environment and cause aloss of catalytic activity. Extended exposure of catalytic sites to suchconditions generally results in irreversible loss of catalytic activityto the exposed site. At a certain point, the molecular sieve is not ofpractical use in a large scale catalytic process. As defined herein, alarge scale catalytic process is one having a reactor loading in excessof 50 kg, particularly one having a reactor system loading in excess of500 kg, especially one having a reactor loading in excess of 5000 kg.

[0034] Extended exposure, or the point at which loss of catalyticactivity becomes undesirable, is defined according to this invention bya methanol uptake index. According to this invention, the methanoluptake index is defined as the ratio between the maximum methanoladsorption capacity (wt %) of an activated SAPO molecular sieve (i.e.,the initial methanol adsorption capacity) and the methanol adsorptioncapacity (wt %) of the activated SAPO molecular sieve at the time ofcatalytic contact with a feedstock (i.e., the methanol adsorptioncapacity at feed contact). At the time of catalytic contact with afeedstock marks the end of the production-to-use chain.

[0035] At the time of catalytic contact means the point in time when theactivated SAPO molecular sieve is contacted with feed under conditionseffective to convert the feed to product, the product containingmeasurable portions of ethylene and propylene. This does not imply,however, that the methanol adsorption capacity at feed contact must becalculated at the exact instant that feed contacts activated molecularsieve. This is because it may not be possible to run such a precisecalculation, particularly in evaluating large scale reaction systems.Therefore, the methanol adsorption capacity at feed contact must beevaluated as soon as practical before contact with feed. For molecularsieve activated in situ, the time between activation and actual contactwith feed is short enough such that the initial methanol adsorptioncapacity is essentially equivalent to the methanol adsorption capacityat feed contact, resulting in a methanol uptake index ofapproximately 1. For ex situ activation, the methanol adsorptioncapacity at feed contact should be evaluated as close as practical toactual contact with feed under catalytic conversion conditions. Undersome circumstances, especially when dealing with large scale systems, asclose as practical may extend up to as much as 12 hours betweenactivation and actual contact with feed under catalytic conversionconditions.

[0036] According to this invention, it is preferred that the methanoluptake index be at least 0.15, preferably at least 0.4, more preferablyat least 0.6, and most preferably at least 0.8. Although some catalyticactivity can occur at a methanol uptake index below 0.15, the molecularsieve at that state is not of practical value as a commercial scalecatalyst. Irreversible loss of catalytic activity will likely occurbelow this point to the extent that the catalyst is no longer of benefitin a large scale catalytic process.

[0037] The catalytic activity of the molecular sieve for use as acatalyst for converting oxygenate to olefin product is consideredsufficiently preserved or protected when the molecular sieve has thedesired methanol uptake index at time of contact with oxygenate underconditions effective to convert the oxygenate to olefin product. Sincethe methanol uptake index will drop over time if the molecular sieve isimproperly handled, contact with oxygenate under reaction conditionsshould occur before the methanol uptake index drops below 0.15.

[0038] To calculate methanol uptake index, methanol adsorption capacitymust be measured. Techniques for measuring methanol adsorption capacityare known to those of ordinary skill in the art. In a preferredtechnique, about 5 mg of sample is introduced into a thermogravimetricanalyzer (TGA). The sample is subjected to a heat treatment process,which includes: (1) heating from room temperature to 450° C., with aheat up rate of 20° C./min. in air; (2) holding at 450° C. for 40 min.in air; and cooling to 30° C. in air. After the sample has reached 30°C., the air flow is switched to a methanol containing nitrogen flow witha methanol partial pressure of 0.09 atm. The sample is contacted withthis nitrogen/methanol mixture for 180 minutes. The methanol adsorptioncapacity is the weight percent weight increase after the 180 minutescontact with the methanol vapor.

[0039] To obtain a SAPO molecular sieve having the appropriate methanoluptake index, the shield can be removed in situ. That is, the shield,whether template, carbonaceous material or anhydrous liquid or gas, canbe removed inside the reactor or the regenerator during operation.However, in a preferred embodiment, the template or carbonaceousmaterial is removed ex situ. This means that it is preferred to activatethe catalytic sites of the molecular sieve outside of the reactor. Thisis because there is less likelihood that the shield material willcontaminate the reaction products. This is particularly beneficial whenthe desired product of the methanol reaction process is to be very lowin any nitrogen or sulfur-containing contaminants. For example, in caseswhere the shield is a molecular sieve template containing a nitrogencomponent and the desired product of the reaction process is ethylene,it may be desirable to remove the template ex situ since the presence ofvery small amounts of nitrogen in the ethylene might adversely impactthe subsequent conversion of the ethylene product to polyethylene. Inless sensitive reaction systems, however, catalyst containing a templatematerial can be added as makeup and activated in situ. Even in moresensitive reaction processes, makeup addition can be directly to thereactor, i.e., in situ addition, since makeup addition can be controlledto add catalyst at relatively low quantities over a period of time,thereby minimizing possible product contamination. Preferably, themakeup addition is directly to a return line which sends regeneratedcatalyst from the regenerator back to the reactor, or addition is to theregenerator itself. Addition of catalyst outside of the reactor itselfis considered ex situ addition, which includes addition at the returnline or the regenerator.

[0040] When ex situ activation of the molecular sieve is carried out, itis important to not let the methanol uptake index drop below thedesirable value of 0.15, preferably 0.4, more preferably 0.6, and mostpreferably 0.8, before using the molecular sieve in a reaction process.As mentioned above, this is because irreversible loss of catalyticactivity, which is represented by a significant drop in methanol uptakeindex as well as methanol conversion, will reach a level that isundesirable for practical operation.

[0041] It has also been found that once the activated catalyst is loadedinto a heated system, whether reactor, regenerator or any other part ofthe operating system, or any type of storage environment, loss ofcatalyst activity is greatly reduced, even when a shield is not present.At a temperature of at least about 150° C., catalyst activity has beenfound to be stabilized. This means that at a temperature of 150° C. orabove, moisture has very little impact on active catalyst sites. It ispreferred to maintain active molecular sieve at a temperature of 150 to800° C., more preferably at a temperature of 175-600° C., and mostpreferably at a temperature of 200-500° C. in order to maintain catalystactivity.

[0042] Undesirable drops in methanol uptake index can be controlled byproper handling during storage or transport. In environments maintainedbelow 150° C., this means that as long as there is sufficient shieldingof the catalytic sites before use in a catalytic process, catalyticactivity will be acceptable. Sufficient shielding can be maintained bystoring or transporting the molecular sieve or catalyst containing themolecular sieve with its template or with an acceptable carbonaceousmaterial which shields the catalytic sites from contact with moisture.Even when activated, sufficient shielding can be maintained by storingor transporting the activated molecular sieve or catalyst containing themolecular sieve in an anhydrous environment.

[0043] It is also preferable that the activated SAPO molecular sievehave a methanol conversion of at least 10 wt. %, preferably at least 15wt. %, most preferably at least 20 wt. %, at standard methanolconversion conditions. For purposes of this invention, standard methanolconversion conditions means that methanol conversion is determined at atime on stream (TOS) of 5 minutes and a WHSV of 24 hr⁻¹. As definedherein, methanol conversion is the weight percent of methanol convertedto product, with any dimethyl ether present in the product not beingincluded as part of the converted product. The method for calculatingmethanol conversion is carried out using a standard ½″ diameter SS,fixed bed, continuous reactor. A sample of the molecular sieve or acatalyst containing the molecular sieve is added to the reactor and 100%methanol is added as feed. The reaction is carried out at 450° C., areactor pressure of 25 psig (i.e., a methanol partial pressure of 25psig), and a weight hourly space velocity (WHSV) of 25 hr⁻¹. Thereaction products are preferably analyzed with an on-line gaschromatograph (GC). After 5 minutes time on stream (i.e., after 5minutes of contacting methanol with molecular sieve under reactionconditions), methanol conversion is calculated as: 100−(wt. %methanol+wt. % DME) left in the product.

[0044] In testing for the methanol conversion, WHSV is defined as theweight of the feed fed to the ½″ reactor over time (per hour) divided bythe weight of the silicoaluminophosphate molecular sieve component ofthe catalyst in the reactor. The silicoaluminophosphate molecular sievecomponent of the catalyst is intended to mean only thesilicoaluminophosphate molecular sieve portion that is contained withinthe catalyst. This excludes catalyst components such asnon-silicoaluminophosphate molecular sieves, binders, diluents, inerts,rare earth components, etc.

[0045] The silicoaluminophosphate molecular sieves of this inventioncomprise a three-dimensional microporous crystal framework structure of[SiO₂], [AlO₂] and [PO₂] tetrahedral units. The way Si is incorporatedinto the structure can be determined by ²⁹Si MAS NMR. See Blackwell andPatton, J. Phys. Chem., 92, 3965 (1988). The desired SAPO molecularsieves will exhibit one or more peaks in the ²⁹Si MAS NMR, with achemical shift [(Si) in the range of −88 to −94 ppm and with a combinedpeak area in that range of at least 20% of the total peak area of allpeaks with a chemical shift [(Si) in the range of −88 ppm to −115 ppm,where the [(Si) chemical shifts refer to external tetramethylsilane(TMS).

[0046] Silicoaluminophosphate molecular sieves are generally classifiedas being microporous materials having 8, 10, or 12 membered ringstructures. These ring structures can have an average pore size rangingfrom about 3.5-15 angstroms. Preferred are the small pore SAPO molecularsieves having an average pore size ranging from about 3.5 to 5angstroms, more preferably from 4.0 to 5.0 angstroms. These preferredpore sizes are typical of molecular sieves having 8 membered rings.

[0047] In general, silicoaluminophosphate molecular sieves comprise amolecular framework of corner-sharing [SiO₂], [AlO₂], and [PO₂]tetrahedral units. This type of framework is effective in convertingvarious oxygenates into olefin products.

[0048] The [PO₂] tetrahedral units within the framework structure of themolecular sieve of this invention can be provided by a variety ofcompositions. Examples of these phosphorus-containing compositionsinclude phosphoric acid. organic phosphates such as triethyl phosphate,and aluminophosphates. The phosphorous-containing compositions are mixedwith reactive silicon and aluminum-containing compositions under theappropriate conditions to form the molecular sieve.

[0049] The [AlO₂] tetrahedral units within the framework structure canbe provided by a variety of compositions. Examples of thesealuminum-containing compositions include aluminum alkoxides such asaluminum isopropoxide, aluminum phosphates, aluminum hydroxide, sodiumaluminate, and pseudoboehmite. The aluminum-containing compositions aremixed with reactive silicon and phosphorus-containing compositions underthe appropriate conditions to form the molecular sieve.

[0050] The [SiO₂] tetrahedral units within the framework structure canbe provided by a variety of compositions. Examples of thesesilicon-containing compositions include silica sols and siliciumalkoxides such as tetra ethyl orthosilicate. The silicon-containingcompositions are mixed with reactive aluminum and phosphorus-containingcompositions under the appropriate conditions to form the molecularsieve.

[0051] Substituted SAPOs can also be used in this invention. Thesecompounds are generally known as MeAPSOs or metal-containingsilicoaluminophosphates. The metal can be alkali metal ions (Group IA),alkaline earth metal ions (Group IIA), rare earth ions (Group IIIB,including the lanthanoid elements: lanthanum, cerium, praseodymium,neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium,erbium, thulium, ytterbium and lutetium; and scandium or yttrium) andthe additional transition cations of Groups IVB, VB, VIB, VIIB, VIIIB,and IB.

[0052] Preferably, the Me represents atoms such as Zn, Mg, Mn, Co, Ni,Ga, Fe, Ti, Zr, Ge, Sn, and Cr. These atoms can be inserted into thetetrahedral framework through a [MeO₂] tetrahedral unit. The [MeO₂]tetrahedral unit carries a net electric charge depending on the valencestate of the metal substituent. When the metal component has a valencestate of +2, +3, +4, +5, or +6, the net electric charge is between −2and +3. Incorporation of the metal component is typically accomplishedadding the metal component during synthesis of the molecular sieve.However, post-synthesis ion exchange can also be used.

[0053] Suitable silicoaluminophosphate molecular sieves include SAPO-5,SAPO-8, SAPO-11, SAPO-16, SAPO-17, SAPO-18, SAPO-20, SAPO-31, SAPO-34,SAPO-35, SAPO-36, SAPO-37, SAPO-40, SAPO-41, SAPO-42, SAPO-44, SAPO-47,SAPO-56, the metal containing forms thereof, and mixtures thereofPreferred are SAPO-18, SAPO-34, SAPO-35, SAPO-44, and SAPO-47,particularly SAPO-18 and SAPO-34, including the metal containing formsthereof, and mixtures thereof. As used herein, the term mixture issynonymous with combination and is considered a composition of matterhaving two or more components in varying proportions, regardless oftheir physical state.

[0054] The silicoaluminophosphate molecular sieves are synthesized byhydrothermal crystallization methods generally known in the art. See,for example, U.S. Pat. Nos. 4,440,871; 4,861,743; 5,096,684; and5,126,308, the methods of making of which are fully incorporated hereinby reference. A reaction mixture is formed by mixing together reactivesilicon, aluminum and phosphorus components, along with at least onetemplate. Generally the mixture is sealed and heated, preferably underautogenous pressure, to a temperature of at least 100° C., preferablyfrom 100-250° C., until a crystalline product is formed. Formation ofthe crystalline product can take anywhere from around 2 hours to as muchas 2 weeks. In some cases, stirring or seeding with crystalline materialwill facilitate the formation of the product.

[0055] Typically, the molecular sieve product will be formed insolution. It can be recovered by standard means, however, such as bycentrifugation or filtration. The product can also be washed, recoveredby the same means and dried.

[0056] As a result of the crystallization process, the recovered sievecontains within its pores at least a portion of the template used inmaking the initial reaction mixture. The crystalline structureessentially wraps around the template, and the template must be removedto obtain catalytic activity. Once the template is removed, thecrystalline structure that remains has what is typically called anintracrystalline pore system.

[0057] The SAPO molecular sieve can contain one or more templates.Templates are structure directing agents, and typically containnitrogen, phosphorus, oxygen, carbon, hydrogen or a combination thereof,and can also contain at least one alkyl or aryl group, with 1 to 8carbons being present in the alkyl or aryl group. Mixtures of two ormore templates can produce mixtures of different sieves or predominantlyone sieve where one template is more strongly directing than another.

[0058] Representative templates include tetraethyl ammonium salts,cyclopentylamine, aminomethyl cyclohexane, piperidine, triethylamine,cyclohexylamine, tri-ethyl hydroxyethylamine, morpholine, dipropylamine(DPA), pyridine, isopropylamine and combinations thereof. Preferredtemplates are triethylamine, cyclohexylamine, piperidine, pyridine,isopropylamine, tetraethyl ammonium salts, and mixtures thereof. Thetetraethylammonium salts include tetraethyl ammonium hydroxide (TEAOH),tetraethyl ammonium phosphate, tetraethyl ammonium fluoride, tetraethylammonium bromide, tetraethyl ammonium chloride, tetraethyl ammoniumacetate. Preferred tetraethyl ammonium salts are tetraethyl ammoniumhydroxide and tetraethyl ammonium phosphate.

[0059] In this invention, the templates can be used to shield thecatalytic sites of the SAPO molecular sieve from contact with watermolecules. Since the templates will be present within the microporousstructure of the sieve, water molecules will not be able to enter thepores of the sieve, preventing any contact with the catalyst sites. Thismeans that a molecular sieve containing a template can even be stored inwet filter cake form, without noticeable loss of catalytic activity onceactivated. When stored in wet filter cake form, the molecular sieve willtypically be dried without removing the template. Then, the molecularsieve can be calcined to remove the template.

[0060] Carbonaceous material can also be used to shield the catalyticsites of the SAPO molecular sieve. In this embodiment, carbonaceousmaterial can be within the microcrystalline pore structure or it can bedeposited to cover the pore entrance. The carbonaceous material can beplaced within the crystalline pore structure by partially burning thetemplate material so that carbon residue remains within the molecularsieve. Carbonaceous material can also be directly applied to theexterior of the molecular sieve to block the pore openings.

[0061] As is known in the art, molecular sieve or catalyst containingthe molecular sieve, must be activated prior to use in a catalyticprocess. Activation is performed in such a manner that template isremoved from the molecular sieve, leaving active catalytic sites withthe microporous channels of the molecular sieve open for contact withfeed. The activation process is typically accomplished by calcining, oressentially heating the template at a temperature of from 200 to 800° C.in the presence of an oxygen-containing gas. In some cases, it may bedesirable to heat in an environment having a low oxygen concentration.This type of process can be used for partial or complete removal of thetemplate from the intracrystalline pore system. In other cases,particularly with smaller templates, complete or partial removal fromthe sieve can be accomplished by conventional desorption processes suchas those used in making standard zeolites.

[0062] Once the molecular sieve or catalyst containing the molecularsieve has been activated, an anhydrous environment can be provided as ashield against water molecules contacting catalyst sites within themolecular sieve. Such an environment can be provided by covering thesieve with a gas or liquid blanket under anhydrous conditions. Asprovided herein, the anhydrous gas or liquid blanket will have a limitedamount of water. The anhydrous gas blanket can be provided under vacuumconditions or under atmospheric or greater pressure conditions, and willhave less than about 1.2 volume percent water, preferably less thanabout 0.2 volume percent water, more preferably less than about 0.02volume percent water. The anhydrous liquid blanket will have less thanabout 200 ppm water preferably less than about 100 ppm water, morepreferably less than about 50 ppm water. The anhydrous environment canbe applied during storage, transport or loading of the catalyst.

[0063] The anhydrous gas blanket is one which is a gas under standardtemperature and pressure conditions and does not react to anysignificant degree with the molecular sieve structure. The gas ispreferably selected from the group consisting of nitrogen, helium, CO,CO₂, H₂, argon, O₂, light alkanes (especially C₁-C₄ alkanes,particularly methane and ethane), cyclo-alkanes and mixtures thereof,e.g. air. The gas blanket can be maintained at any pressure, includingunder vacuum or at pressures above standard, even if the gas becomesliquid at pressures above standard, as long as the conditions remainanhydrous.

[0064] The anhydrous liquid blanket is a liquid under standardtemperature and pressure conditions, and does not react to anysignificant degree with the molecular sieve structure. The liquid ispreferably selected from the group consisting of alkanes, cyclo-alkanes,C₆-C₃₀ aromatics, alcohols, particularly C₄ ⁺ branched alcohols.

[0065] In this invention, the molecular sieve is made ready for use in acatalytic process by removing the shielding conditions. If the gas orliquid blanket is applied under anhydrous conditions to shield analready activated molecular sieve, the blanket or liquid need merely beremoved by any standard technique. This can be as simple as merelyopening the blanketed system to the atmosphere or by using any standardfiltration or separation technique.

[0066] If a carbonaceous material is used as the shield, it can also beremoved by exposing the sieve to sufficient temperature conditions todecompose the carbonaceous material. Preferably, the carbonaceousmaterial is removed by calcining at a temperature of about 200-800° C.

[0067] It is preferred that the molecular sieve not be exposed tohydrous conditions once the shield is removed. Otherwise, there may beirreversible catalytic loss. However, the molecular sieve can be stored,transported or loaded into a reactor system, in its unshielded form, ina hydrous environment as long as the methanol uptake index does not fallbelow 0.15, preferably 0.4, more preferably 0.6, most preferably 0.8.

[0068] The silicoaluminophosphate molecular sieves may be admixed(blended) with other materials. When blended, the resulting compositionis typically referred to as a silicoaluminophosphate (SAPO) catalyst,with the catalyst comprising the SAPO molecular sieve.

[0069] Materials which can be blended with the molecular sieve can bevarious inert or catalytically active materials, or various bindermaterials. These materials include compositions such as kaolin and otherclays, various forms of rare earth metals, other non-zeolite catalystcomponents, zeolite catalyst components, alumina or alumina sol,titania, zirconia, quartz, silica or silica or silica sol, and mixturesthereof. These components are also effective in reducing overallcatalyst cost, acting as a thermal sink to assist in heat shielding thecatalyst during regeneration, densifying the catalyst and increasingcatalyst strength. When blended with non-silicoaluminophosphatemolecular sieve materials, the amount of molecular sieve which iscontained in the final catalyst product ranges from 10 to 90 weightpercent of the total catalyst, preferably 30 to 70 weight percent of thetotal catalyst.

[0070] In one embodiment of this invention, a feed containing anoxygenate is contacted in a reaction zone of a reactor apparatus with anactivated molecular sieve catalyst at process conditions effective toproduce light olefins, i.e., an effective temperature, pressure, WHSV(weight hour space velocity) and, optionally, an effective amount ofdiluent, correlated to produce light olefins. Typically, the oxygenatefeed is contacted with the catalyst when the oxygenate is in a vaporphase. However, the process may be carried out in a liquid or a mixedvapor/liquid phase. When the process is carried out in a liquid phase ora mixed vapor/liquid phase, different conversions and selectivities offeed-to-product may result depending upon the catalyst and reactionconditions.

[0071] Olefins can generally be produced at a wide range oftemperatures. An effective operating temperature range can be from about200° C. to 700° C. At the lower end of the temperature range, theformation of the desired olefin products may become markedly slow. Atthe upper end of the temperature range, the process may not form anoptimum amount of product. An operating temperature of at least 300° C.,and up to 500° C. is preferred.

[0072] Owing to the nature of the process, it may be desirable to carryout the process of the present invention by use of the molecular sievecatalysts in a dynamic bed system or any system of a variety oftransport beds rather than in a fixed bed system. It is particularlydesirable to operate the reaction process at high space velocities.

[0073] The conversion of oxygenates to produce light olefins may becarried out in a variety of large scale catalytic reactors, including,but not limited to, fluid bed reactors and concurrent riser reactors asdescribed in “Free Fall Reactor,” Fluidization Engineering, D. Kunii andO. Levenspiel, Robert E. Krieger Publishing Co. NY, 1977, incorporatedin its entirety herein by reference. Additionally, countercurrent freefall reactors may be used in the conversion process. See, for example,U.S. Pat. No. 4,068,136 and “Riser Reactor”, Fluidization andFluid-Particle Systems, pages 48-59, F. A. Zenz and D. F. Othmo,Reinhold Publishing Corp., NY 1960, the descriptions of which areexpressly incorporated herein by reference.

[0074] Any standard commercial scale reactor system can be used,including fixed bed or moving bed systems. The commercial scale reactorsystems can be operated at a weight hourly space velocity (WHSV) of from1 hr⁻¹ to 1000 hr⁻¹. In the case of commercial scale reactors, WHSV isdefined as the weight of hydrocarbon in the feed per hour per weight ofsilicoaluminophosphate molecular sieve content of the catalyst. Thehydrocarbon content will be oxygenate and any hydrocarbon which mayoptionally be combined with the oxygenate. The silicoaluminophosphatemolecular sieve content is intended to mean only thesilicoaluminophosphate molecular sieve portion that is contained withinthe catalyst. This excludes components such as binders, diluents,inerts, rare earth components, etc.

[0075] It is highly desirable to operate at a temperature of at least300° C. and a Temperature Corrected Normalized Methane Sensitivity(TCNMS) of less than about 0.016, preferably less than about 0.012, morepreferably less than about 0.01. It is particularly preferred that thereaction conditions for making olefin from oxygenate comprise a WHSV ofat least about 20 hr⁻¹ producing olefins and a TCNMS of less than about0.016.

[0076] As used herein, TCNMS is defined as the Normalized MethaneSelectivity (NMS) when the temperature is less than 400° C. The NMS isdefined as the methane product yield divided by the ethylene productyield wherein each yield is measured on, or is converted to, a weight %basis. When the temperature is 400° C. or greater, the TCNMS is definedby the following equation, in which T is the average temperature withinthe reactor in ° C.:${TCNMS} = \frac{NMS}{1 + \left( {\left( {\left( {T - 400} \right)/400} \right) \times 14.84} \right)}$

[0077] The pressure also may vary over a wide range, includingautogenous pressures. Effective pressures may be in, but are notnecessarily limited to, pressures of from about 0.1 kPa to about 10 MPa.Preferred pressures are in the range of about 5 kPa to about 5 MPa, withthe most preferred range being of from about 50 kPa to about 0.5 MPa.The foregoing pressures are exclusive of any oxygen depleted diluent,and thus, refer to the partial pressure of the oxygenate compoundsand/or mixtures thereof with feedstock. At the lower and upper end ofthe foregoing pressure ranges, the rate of selectivity, conversionand/or reaction may not be optimum.

[0078] One or more inert diluents may be present in the feedstock, forexample, in an amount of from 1 to 99 molar percent, based on the totalnumber of moles of all feed and diluent components fed to the reactionzone (or catalyst). Typical diluents include, but are not necessarilylimited to helium, argon, nitrogen, carbon monoxide, carbon dioxide,hydrogen, water, paraffins, alkanes (especially methane, ethane, andpropane), alkylenes, aromatic compounds, and mixtures thereof. Thepreferred diluents are water and nitrogen. Water can be injected ineither liquid or vapor form.

[0079] The process may be carried out in a batch, semi-continuous orcontinuous fashion. The process can be conducted in a single reactionzone or a number of reaction zones arranged in series or in parallel.

[0080] The level of conversion of the oxygenates can be maintained toreduce the level of unwanted by-products. Conversion can also bemaintained sufficiently high to avoid the need for commerciallyundesirable levels of recycling of unreacted feeds. A reduction inunwanted by-products is seen when conversion moves from 100 mol % toabout 98 mol % or less. Recycling up to as much as about 50 mol % of thefeed is commercially acceptable. Therefore, conversions levels whichachieve both goals are from about 50 mol % to about 98 mol % and,desirably, from about 85 mol % to about 98 mol %. However, it is alsoacceptable to achieve conversion between 98 mol % and 100 mol % in orderto simplify the recycling process. Oxygenate conversion may bemaintained at this level using a number of methods familiar to personsof ordinary skill in the art. Examples include, but are not necessarilylimited to, adjusting one or more of the following: the reactiontemperature; pressure; flow rate (i e., WHSV); level and degree ofcatalyst regeneration; amount of catalyst re-circulation; the specificreactor configuration; the feed composition; and other parameters whichaffect the conversion.

[0081] If regeneration is required, the molecular sieve catalyst can becontinuously introduced as a moving bed to a regeneration zone where itcan be regenerated, such as for example by removing carbonaceousmaterials or by oxidation in an oxygen-containing atmosphere. In apreferred embodiment, the catalyst is subject to a regeneration step byburning off carbonaceous deposits accumulated during the conversionreactions.

[0082] The oxygenate feedstock comprises at least one organic-compoundwhich contains at least one oxygen atom, such as aliphatic alcohols,ethers, carbonyl compounds (aldehydes, ketones, carboxylic acids,carbonates, esters and the like), and the feedstock may optionallycontain at least one compound containing a halide, mercaptan, sulfide,or amine, as long as the optional components do not significantly impedethe performance of the catalyst. When the oxygenate is an alcohol, thealcohol can include an aliphatic moiety having from 1 to 10 carbonatoms, more preferably from 1 to 4 carbon atoms. Representative alcoholsinclude but are not necessarily limited to lower straight and branchedchain aliphatic alcohols, their unsaturated counterparts and thenitrogen, halogen and sulfur analogues of such. Examples of suitableoxygenate compounds include, but are not limited to: methanol; ethanol;n-propanol; isopropanol; C₄-C₂₀ alcohols; methyl ethyl ether; dimethylether; diethyl ether; di-isopropyl ether; formaldehyde; dimethylcarbonate; dimethyl ketone; acetic acid; and mixtures thereof. Preferredoxygenate compounds are methanol, dimethyl ether, or a mixture thereof.

[0083] The method of making the preferred olefin product in thisinvention can include the additional step of making these compositionsfrom hydrocarbons such as oil, coal, tar sand, shale, biomass andnatural gas. Methods for making the compositions are known in the art.These methods include fermentation to alcohol or ether, making synthesisgas, then converting the synthesis gas to alcohol or ether. Synthesisgas can be produced by known processes such as steam reforming,autothermal reforming and partial oxidization.

[0084] One skilled in the art will also appreciate that the olefinsproduced by the oxygenate-to-olefin conversion reaction of the presentinvention can be polymerized to form polyolefins, particularlypolyethylene and polypropylene. Processes for forming polyolefins fromolefins are known in the art. Catalytic processes are preferred.Particularly preferred are metallocene, Ziegler/Natta and acid catalyticsystems. See, for example, U.S. Pat. Nos.3,258,455; 3,305,538;3,364,190; 5,892,079; 4,659,685; 4,076,698; 3,645,992; 4,302,565; and4,243,691, the catalyst and process descriptions of each being expresslyincorporated herein by reference. In general, these methods involvecontacting the olefin product with a polyolefin-forming catalyst at apressure and temperature effective to form the polyolefin product.

[0085] A preferred polyolefin-forming catalyst is a metallocenecatalyst. The preferred temperature range of operation is between 50 and240° C. and the reaction can be carried out at low, medium or highpressure, being anywhere within the range of about 1 to 200 bars. Forprocesses carried out in solution, an inert diluent can be used, and thepreferred operating pressure range is between 10 and 150 bars, with apreferred temperature range of between 120 and 230° C. For gas phaseprocesses, it is preferred that the temperature generally be within arange of 60 to 160° C., and that the operating pressure be between 5 and50 bars.

[0086] This invention will be better understood with reference to thefollowing examples, which are intended to illustrate specificembodiments within the overall scope of the invention as claimed.

EXAMPLE 1

[0087] Samples of SAPO-34 containing a morpholine template were heatedin order to remove the template. One sample was heated for 5 hours at650° C. in N₂ followed by 3 hours at 650° C. in air in a closed furnaceto remove the template. The sample was stored for 4 days over silica gel(relative humidity <20% at 20° C.). A second sample was heated in thesame manner, but was stored for 3 days at 80% relative humidity and 20°C. In a third sample, the template was removed in the same manner.However, the third sample was transferred at 150° C. into a fixed bed,continuous reactor immediately after template removal. The third samplewas designated as the “0 days aged” sample portion. Each portion wasthen individually evaluated in a fixed bed, continuous reactor. Reactiontemperature was maintained at 450° C. Pressure in the reactor was heldat 25 psig. Methanol feed was continuously fed to the reactor at a WHSVof 25 hr⁻¹. Reaction products were analyzed with an on-line GC equippedwith a FID and TCD detector. FIG. 1 shows wt % of methanol converted asa function of TOS (in minutes). The methanol conversion of the firstsample at a TOS of 5 minutes was approximately 27 wt. %. The methanolconversion of the second sample at a TOS of 5 minutes was approximately0 wt. %. the methanol conversion of the third sample at TOS of 5 minuteswas approximately 100 wt. %.

EXAMPLE 2

[0088] Samples of SAPO-34 containing a morpholine template were heatedin order to remove the template. One sample was heated for 5 hours at650° C. in N₂ followed by 3 hours at 650° C. in air in a closed furnaceto remove the template. The sample was stored for 1 day under ambientconditions. A second sample was heated in the same manner, but wasstored for 5 days under ambient conditions. In a third sample, thetemplate was removed in situ (i.e., in a fixed bed, continuous reactor)under nitrogen at 650° C. for 5 hours, followed by air at 650° C. for 3hours. The third sample was designated as the “0 days aged” sampleportion. The sample portions having the templates removed were measuredfor methanol uptake according to the following procedure:

[0089] About 5 mg of sample was introduced into a Perkin Elmer TGS-2thermogravimetric analyzer (TGA). The sample was subjected to heattreatment, which included: (1) heating from room temperature to 450° C.,with a heat up rate of 20° C./min. in air; (2) holding at 450° C. for 40min. in air; and cooling to 30° C. in air. After the sample reached 30°C., the air flow was switched to a methanol containing nitrogen flowwith a methanol partial pressure of 0.09 atm. The sample was thencontacted with this nitrogen/methanol mixture for 180 minutes, and themethanol adsorption capacity was calculated as the weight percentincrease after the 180 minutes contact with the methanol vapor. FIG. 2shows methanol adsorption capacity or methanol uptake as a function oftime. The horizontal line fragments indicate the saturation level.

[0090] The methanol uptake index was calculated based on the saturationlevel aged samples versus the saturation level of the “0 days aged/insitu” sample. The 0 days aged/in situ sample was defined as the basecase, having a methanol uptake index of 1. The methanol uptake index forthe 1 day lab aged sample was calculated as approximately 0.85, and themethanol uptake index for the 5 days lab aged sample was calculated asapproximately 0.65.

EXAMPLE 3

[0091] A sample of SAPO-34 containing a DPA/TEAOH template was dried,with the template being left in place. The sample was stored for 25days, then mixed with SiC (0.36 g SAPO/5 g SiC). The template was thenremoved in situ (i.e., in a fixed bed, continuous reactor) undernitrogen at 625° C. for 1 hour. After template removal, methanol wascontinuously fed to the reactor at a WHSV of 25 hr⁻¹ while maintainingthe reaction temperature at 450° C. and the reactor pressure at 23 psig.Reaction products were analyzed with an on-line GC equipped with a FIDand TCD detector for ethylene and propylene yield. Methanol conversionwas calculated as: 100−(wt % methanol+DME) left in product. The data areshown in FIG. 3, with the label “fresh, calcined sieve.”

EXAMPLE 4

[0092] A sample of SAPO-34 containing a DPA/TEAOH template was filteredand stored in a wet filter cake form, with the template being left inplace. After storing for 44 days, the filter cake was dried, then thetemplate was then removed and methanol conversion calculated accordingto the procedure of Example 3. The data are shown in FIG. 3.

EXAMPLE 5

[0093] A sample of SAPO-34 containing a DPA/TEAOH template was filteredand stored in a wet filter cake form, with the template being left inplace. After storing for 73 days, the filter cake was dried, then thetemplate was then removed and methanol conversion calculated accordingto the procedure of Example 3. The data are shown in FIG. 3.

EXAMPLE 6

[0094] A sample of SAPO-34 containing a DPA/TEAOH template was dried,with the template being left in place. The sample was stored for 132days under ambient conditions. The template was then removed andmethanol conversion calculated according to the procedure of Example 3.The data are shown in FIG. 3.

EXAMPLE 7

[0095] A detemplated SAPO-34 was aged under ambient conditions for 18months. Methanol adsorption capacity was determined according to theprocedure of Example 2. From the initial methanol adsorption capacityand the methanol adsorption capacity at feed contact, the methanoluptake index was calculated as 0.12.

[0096] Methanol conversion of a sample of the 18 months aged SAPO-34 wasevaluated according to the procedure of Example 3. At a TOS of 2minutes, the methanol conversion was 26.97 wt. %. At a TOS of 5 minutes,the methanol conversion had significantly dropped to 0.63 wt. %.

[0097] The data indicate that a silicoaluminophosphate molecular sievehaving a methanol uptake index of 0.12 is catalytically active for abrief period of time. However, the catalytic activity of such amolecular sieve drops off very quickly, indicating that a molecularsieve having such a low methanol uptake index is less desirable forreaction systems, as it will tend to increase the frequency at which themolecular sieve will need to be regenerated.

[0098] Having now fully described this invention, it will be appreciatedby those skilled in the art that the invention can be performed within awide range of parameters within what is claimed, without departing fromthe spirit and scope of the invention.

What is claimed is:
 1. A method of making an olefin product from anoxygenate feedstock, comprising providing a silicoaluminophosphatemolecular sieve having catalytic sites within the molecular sieve;providing a shield to protect the catalytic sites from contact withwater molecules; removing the shield; and, after removing the shield,contacting the sieve with an oxygenate feedstock under conditionseffective to produce an olefin product, wherein the activated sievecontacting the oxygenate feedstock has a methanol uptake index of atleast 0.15.
 2. The method of claim 1, wherein the methanol uptake indexis at least 0.4.
 3. The method of claim 2, wherein the methanol uptakeindex is at least 0.6.
 4. The method of claim 3, wherein the methanoluptake index is at least 0.8.
 5. The method of claim 1, wherein thesieve contacting the feedstock has a methanol conversion of at least 10wt. % at a standard time on stream of 5 minutes and a WHSV of 25 hr⁻¹.6. The method of claim 5, wherein the sieve contacting the feedstock hasa methanol conversion of at least 15 wt. % at a standard time on streamof 5 minutes and a WHSV of 25 hr⁻¹.
 7. The method of claim 6, whereinthe sieve contacting the feedstock has a methanol conversion of at least20 wt. % at a standard time on stream of 5 minutes and a WHSV of 25hr⁻¹.
 8. The method of claim 1, wherein the sieve is maintained at atemperature of at least 150° C. prior to contacting with feedstock. 9.The method of claim 1, wherein the shield is removed ex situ.
 10. Themethod of claim 1, wherein the shield is removed in situ.
 11. The methodof claim 1, wherein the shield is a template.
 12. The method of claim11, wherein the template is selected from the group consisting of atetraethyl ammonium salt, cyclopentylamine, aminomethyl cyclohexane,piperidine, triethylamine, cyclohexylamine, tri-ethyl hydroxyethylamine,morpholine, dipropylamine, pyridine, isopropylamine and mixturesthereof.
 13. The method of claim 11, wherein the template is removed bycontacting with an oxygen-containing gas under conditions effective tocalcine the molecular sieve.
 14. The method of claim 11, wherein thetemplate is provided with the molecular sieve as a wet filter cake. 15.The method of claim 14, wherein the template is removed prior tocontacting the molecular sieve with oxygenate feedstock by drying thewet filter cake to obtain a dried material, and then contacting thedried material with an oxygen-containing gas under conditions effectiveto calcine the molecular sieve.
 16. The method of claim 11, wherein thetemplate is removed by contacting with an inert gas, substantially inthe absence of O₂, under conditions effective to remove the templatefrom the molecular sieve.
 17. The method of claim 1, wherein the shieldis an anhydrous gas or liquid.
 18. The method of claim 17, wherein theshield is an anhydrous gas.
 19. The method of claim 18, wherein theanhydrous gas comprises a gas selected from the group consisting ofnitrogen, helium, CO, CO₂, H₂, argon, O₂, light alkanes, and mixturesthereof.
 20. The method of claim 17, wherein the shield is an anhydrousliquid.
 21. The method of claim 20, wherein the anhydrous liquid isselected from the group consisting of alkanes, cyclo-alkanes, C₆-C₃₀aromatics, alcohols and mixtures thereof.
 22. The method of claim 20,wherein the anhydrous liquid is removed and the molecular sieve iscontacted with an oxygen-containing gas under conditions effective tocalcine the molecular sieve prior to contacting the molecular sieve withoxygente feedstock.
 23. The method of claim 1, wherein the shield is acarbonaceous material.
 24. The method of claim 17, wherein the shield isprovided under vacuum conditions.
 25. The method of claim 1, wherein themolecular sieve has a pore size of less than 5 angstroms.
 26. The methodof claim 1, wherein the silicoaluminophosphate molecular sieve isselected from the group consisting of SAPO-5, SAPO-8, SAPO-11, SAPO-16,SAPO-17, SAPO-18, SAPO-20, SAPO-31, SAPO-34, SAPO-35, SAPO-36, SAPO-37,SAPO-40, SAPO-41, SAPO-42, SAPO-44, SAPO-47, SAPO-56, and metalcontaining forms thereof.
 27. The method of claim 1, wherein theactivated catalyst is contacted with the oxygenate feedstock in areactor at a WHSV of 1 hr⁻¹ to 1000 hr⁻¹.
 28. The method of claim 27,wherein olefins are produced at a TCNMS of less than 0.016.
 29. Themethod of claim 1, wherein the molecular sieve is contacted with theoxygenate feedstock at a pressure of from 0.1 kPa to 100 MPa
 30. TheMethod of claim 1, wherein the oxygenate feedstock is selected from thegroup consisting of methanol; ethanol; n-propanol; isopropanol; C₄-C₂₀alcohols; methyl ethyl ether; dimethyl ether; diethyl ether;di-isopropyl ether; formaldehyde; dimethyl carbonate; dimethyl ketone;acetic acid; and mixtures thereof.
 31. The method of claim 1, whereinthe olefin product comprises ethylene, propylene, or a combinationthereof.
 32. The method of claim 1, wherein the silicoaluminophosphatemolecular sieve is provided with a binder material.
 33. The method ofclaim 1, wherein the olefin product is contacted with apolyolefin-forming catalyst under conditions effective to form apolyolefin.
 34. A method of making an olefin product from an oxygenatefeedstock, comprising removing a template from a silicoaluminophosphatemolecular sieve, and contacting the molecular sieve with the oxygenatefeedstock under conditions effective to convert the feedstock to anolefin product before the methanol uptake index drops below 0.15. 35.The method of claim 34, wherein the molecular sieve is contacted withoxygenate feedstock before the methanol uptake index drops below 0.4.36. The method of claim 35, wherein the molecular sieve is contactedwith oxygenate feedstock before the methanol uptake index drops below0.6.
 37. The method of claim 36, wherein the molecular sieve iscontacted with oxygenate feed stock before the methanol uptake indexdrops below 0.8.
 38. The method of claim 34, wherein the activated sievecontacting the feedstock has a methanol conversion of at least 10 wt. %at a standard time on stream of 5 minutes and a WHSV of 25 hr⁻¹.
 39. Themethod of claim 38, wherein the activated sieve contacting the feedstockhas a methanol conversion of at least 15 wt. % at a standard time onstream of 5 minutes and a WHSV of 25 hr⁻¹.
 40. The method of claim 39,wherein the activated sieve contacting the feedstock has a methanolconversion of at least 20 wt. % at a standard time on stream of 5minutes and a WHSV of 25 hr⁻¹.
 41. The method of claim 34, wherein theactivated sieve is maintained at a temperature of at least 150° C. priorto contacting with feedstock.
 42. The method of claim 34, wherein thetemplate is removed ex situ.
 43. The method of claim 34, wherein thetemplate is removed in situ.
 44. The method of claim 34, wherein thetemplate is selected from the group consisting of a tetraethyl ammoniumsalt, cyclopentylamine, aminomethyl cyclohexane, piperidine,triethylamine, cyclohexylamine, tri-ethyl hydroxyethylamine, morpholine,dipropylamine, pyridine, isopropylamine and mixtures thereof.
 45. Themethod of claim 34, wherein the silicoaluminophosphate molecular sieveis selected from the group consisting of SAPO-5, SAPO-8, SAPO-11,SAPO-16, SAPO-17, SAPO-18, SAPO-20, SAPO-31, SAPO-34, SAPO-35, SAPO-36,SAPO-37, SAPO-40, SAPO-41, SAPO-42, SAPO-44, SAPO-47, SAPO-56, metalcontaining forms thereof, and mixtures thereof.
 46. The method of claim34, wherein the oxygenate feedstock is selected from the groupconsisting of methanol; ethanol; n-propanol; isopropanol; C₄-C₂₀alcohols; methyl ethyl ether; dimethyl ether; diethyl ether;di-isopropyl ether; formaldehyde; dimethyl carbonate; dimethyl ketone;acetic acid; and mixtures thereof.
 47. The method of claim 34, whereinthe silicoaluminophosphate molecular sieve is provided with a bindermaterial.
 48. The method of claim 34, wherein the template is removedfrom the molecular sieve by heating at a temperature between 200° C. and800° C.
 49. The method of claim 34, wherein the molecular sieve isexposed to the oxygenate feedstock at a temperature between 200° C. and700° C.
 50. The method of claim 34, wherein the olefin product iscontacted with a polyolefin-forming catalyst under conditions effectiveto form a polyolefin.